Overview of OpenStreetMap.org

OpenStreetMap (OSM) is dedicated to creating and providing geographic data, such as street maps, worldwide, for free.

Most maps considered "free" actually have legal or technical restrictions on their use. These restrictions hold back anyone from using them in creative, productive or unexpected ways, and make every map a silo of data and effort. OpenStreetMap's open license means that contributors to the map are also the owners of the map data, and map providers can collaborate on a mutually beneficial free datasource.

Over two millions contributors have created the map by on-the-ground surveys, finding existing open data, and tracing aerial imagery. Some use GPS, cameras and their own observations to record the precise locations of roads, buildings, amenities, services, etc. Often, they are creating maps entirely from scratch. Others correct existing data, fine-tuning details like road classifications and ever-changing international boundaries. In some areas (particularly in the United States) there is existing open licensed map data that has been imported into OpenStreetMap, but this data may be inaccurate or out of date. Contributors use local knowledge and aerial images (such as those recently provided to the project by Bing) to correct and refine the accuracy of this data.

To get this data into the maps, OSM provides online map-editing tools for uploading to OSM's huge (and growing daily) database. That data is then processed and will show up within minutes on the detailed street-level maps.

The core value of OpenStreetMap.org is that these maps can be published freely on Web sites, or printed and copied without restriction. The underlying data can be downloaded for free, for developers to use or redistribute in new and exciting ways. There are currently over 1.5 billion nodes, or points, in the dataset, which is a twenty-four gigabyte download.